A NEW APPARATUS FOR MEASURING PARTICLE SIZES OF THE ORDER OF NANOMETER

The present research aims at developing a new method for measuring particle sizes of the order of nanometer (nm) on the raw Si wafer using a light-scattering method with Ar+ laser. According to the analysis for Rayleigh scattering theory, the measuring system was developed with the several optical instruments collecting extremely weak light. And a new measuring method was presented to detect the particle of nm order sizes, scanning the laser beam spot at the surface of Si wafer. And then, it was analyzed shot noise at PMT(Photomultiplier tube), calculated fluctuation of the output voltage due to this, define signal to noise ratio S/N of this measuring method. Consequently, it was verified theoretically that this measuring method is applicable for detecting the particle of nm order sizes, non-destructively. Furthermore, it was carried out detecting for particles on the surface of Si wafer with this system, and it could be detected a voltage signal corresponding to a particle diameter about 20nm.